The present invention relates to the lighting arts. It finds particular application in conjunction with surgical lights and will be described with particular reference thereto. It is to be appreciated, however, that the present invention may also find application in conjunction with lights and illumination sources for other purposes.
Typically, surgical lamps are relatively large in diameter and are suspended by a series of articulated arms. A domed reflector is disposed inside of the light head with a single lamp disposed in such a position that the light reflected by the reflector forms a defined column. Typically, the lamp is disposed at or near the focal point of the reflector. One of the drawbacks of such single reflector systems is that their large precision reflectors are relatively expensive. Another drawback is that the depth or height of the large diameter reflector limits the thinness of the light head.
Normally, an adjustment is provided, such as with a rotatable handle at the center of the face of the light head, to adjust the diameter of the light spot. It is important for the light spot, when focused on a planar surface, to have a consistent uniform intensity at all diameters. Moreover, during a surgical procedure, the surgeon's hands and head often are positioned between the light head and the illuminated surgical zone. Sufficient light must be provided by the rest of the light head not obscured by the surgeon that significant shadows are not cast into the surgical zone. Often, refractors are provided to cause light rays to traverse a multiplicity of paths to improve uniformity and reduce shadows. Although effective, refractors again tend to be expensive, particularly in large diameters.
It is important that illumination is not lost during a surgical procedure, even if the bulb should burn out. To this end, a backup bulb is typically provided. In some light heads, the backup light bulb is near the primary lamp. However, because is it not at the proper position relative to the reflector, the performance of the light head is adversely affected. Some light heads use a mechanical mechanism to swap the positions of the primary and backup lamps. Although satisfactory, mechanisms for changing the position of the bulbs have drawbacks. First, the mechanisms add cost. Second, the mechanisms tend to be bulky and contribute to the thickness of the light head.
The present invention contemplates a new and improved technique for overcoming the above-referenced drawbacks and others.